Double patterning method

ABSTRACT

Disclosed is an improved double patterning method for forming openings (e.g., vias or trenches) or mesas on a substrate. This method avoids the wafer topography effects seen in prior art double patterning techniques by ensuring that the substrate itself is only subjected to a single etch process. Specifically, in the method, a first mask layer is formed on the substrate and processed such that it has a doped region and multiple undoped regions within the doped region. Then, either the undoped regions or the doped region can be selectively removed in order to form a mask pattern above the substrate. Once the mask pattern is formed, an etch process can be performed to transfer the mask pattern into the substrate. Depending upon whether the undoped regions are removed or the doped region is removed, the mask pattern will form openings (e.g., vias or trenches) or mesas, respectively, on the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims the benefit under 35 U.S.C. §120 as adivisional of presently pending U.S. patent application Ser. No.13/555,306 filed on Jul. 23, 2012, the entire teachings of which areincorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present disclosure relates to techniques for forming structures on asubstrate, and more specifically, to embodiments of an improved doublepatterning method for forming openings (e.g., vias or trenches) or mesas(e.g., three dimensional bodies, pillars, bars, etc.) on a substrate.

2. Description of the Related Art

As semiconductor device size scaling continues, the ability to formdevices or components thereof with small dimensions has become more andmore challenging. One solution for achieving high resolution is doublepatterning. Conventional double patterning involves double exposure anddouble etch (DPDE) process. That is, a first mask is formed usingconventional lithographic patterning techniques followed by a first etchprocess. Then, a second mask is formed using conventional lithographicpatterning techniques followed by a second etch process. Unfortunately,the wafer topography after the first etch processes may negativelyimpact the formation of the second mask convention due to reduced depthfocus and result in overlay errors. Therefore, there is a need in theart for an improved double patterning technique that avoids such wafertopography effects.

SUMMARY

In view of the foregoing, disclosed herein are embodiments of animproved double patterning method for forming openings (e.g., vias ortrenches) or mesas (e.g., three dimensional bodies, pillars, bars, etc.)on a substrate. This method avoids the wafer topography effects seen inprior art double patterning techniques by ensuring that the substrateitself is only subjected to a single etch process. Specifically, in theembodiments disclosed herein, a first mask layer is formed on thesubstrate and subjected to multiple masked implantation processes suchthat it has a doped region and multiple undoped regions within (i.e.,defined by) the doped region. Then, either the undoped regions or thedoped region can be selectively removed in order to form a mask patternabove the substrate. Once the mask pattern is formed, an etch processcan be performed to transfer the mask pattern into the substrate.Depending upon whether the undoped regions are removed or the dopedregion is removed, the mask pattern will form openings or mesas,respectively, on the substrate.

Generally, each of the method embodiments disclosed herein can compriseproviding a substrate. This substrate can comprise any materialrequiring patterning. A first mask layer (e.g., an amorphoussemiconductor layer or a polycrystalline semiconductor layer, such as anamorphous silicon layer or a polycrystalline silicon layer) can beformed on the substrate. Then, at least two masked dopant implantationprocesses can be performed in order to form, within the first masklayer, a doped region that laterally surrounds multiple undoped regions.Next, either the undoped regions or the doped region of the first masklayer can be selectively removed in order to form a mask patterndirectly above the substrate. Once the mask pattern is formed, a singleetch process can be performed in order to transfer the mask pattern intothe substrate, thereby forming either openings (e.g., vias or trenches)or mesas (e.g., three dimensional bodies, pillars, bars, etc.) in thesubstrate.

In each of the embodiments disclosed herein, the masked dopantimplantation processes can comprise first forming a second mask layer onthe first mask layer. This second mask layer can be formed and,particularly, patterned such that first portions of the first mask layerare exposed. A first dopant implantation process can then be performedto dope the first portions of the first mask layer. After the firstdopant implantation process, the second mask layer can be removed. Next,a third mask layer can be formed on the first mask layer. This thirdmask layer can be formed and, particularly, patterned such that secondportions of the first mask layer, which traverse the first portions, areexposed. Then, a second dopant implantation process can be performed inorder to dope the exposed second portions of the first mask layer. As aresult, the doped first portions and the doped second portions, whichtraverse the first portions, in combination form the doped region thatlaterally surrounds multiple undoped regions. Once the second dopantimplantation process is performed, the third mask layer can be removed.

As mentioned above, in each of the embodiments disclosed herein, eitherthe multiple undoped regions or the doped region of the first mask layercan be selectively removed in order to form a mask pattern directlyabove the substrate. Depending upon whether the undoped regions areremoved or the doped region is removed, this mask pattern can be usedduring a single etch process to form either openings (e.g., vias ortrenches) or mesas (e.g., three dimensional bodies, pillars, bars,etc.), respectively, on the substrate. To optimize the selective removalprocess, the dopant used in the dopant implantation processes describedabove can be pre-selected to facilitate either selective removal of theundoped regions over the doped region for subsequent formation ofopenings (e.g., vias or trenches) in the substrate or selective removalof the doped region for subsequent formation of mesas (e.g., threedimensional bodies, pillars, bars, etc.) in the substrate.

For example, in one embodiment, the patterning method can compriseproviding a substrate. This substrate can comprise any materialrequiring patterning. A first mask layer can be formed on the substrate.Then, at least two masked dopant implantation processes can be performedin order to form, within the first mask layer, a doped region, whichlaterally surrounds multiple undoped regions. Next, the multiple undopedregions can be selectively removed in order to form a mask pattern abovethe substrate. In this case, the dopant used in the dopant implantationprocesses to form the doped region should be preselected to ensure thatthe undoped regions can be selectively etched over the doped region. Forexample, when the first mask layer comprises an amorphous orpolycrystalline silicon layer, boron or xenon can be preselected as thedopant to be used in the dopant implantation processes because undopedsilicon can be readily selectively etched over boron-doped orxenon-doped silicon. Once the mask pattern is formed, a single etchprocess can be performed in order to transfer the mask pattern into thesubstrate, thereby forming openings (e.g., vias or trenches) in thesubstrate.

In another embodiment, the patterning method can comprise providing asubstrate. Again, this substrate can comprise any material requiringpatterning. A first mask layer can be formed on the substrate. Then, atleast two masked dopant implantation processes can be performed in orderto form, within the first mask layer, a doped region, which laterallysurrounds multiple undoped regions. Next, the doped region can beselectively removed in order to form a mask pattern above the substrate.In this case, the dopant used in the dopant implantation processes toform the doped region should be preselected to ensure that the dopedregion can be selectively etched over the undoped regions. For example,when the first mask layer comprises an amorphous or polycrystallinesilicon layer, arsenic or phosphorous can be preselected as the dopantto be used in the dopant implantation processes because arsenic-doped orphosphorous-doped silicon can be readily selectively etched over undopedsilicon. Once the mask pattern is formed, a single etch process can beperformed in order to transfer the mask pattern into the substrate,thereby forming mesas (e.g., three dimensional bodies, pillars, bars,etc.) in the substrate.

Also disclosed herein are embodiments of a computer program product.This computer program product can comprise a computer-readable mediumhaving computer-readable program code embodied therewith. Thecomputer-readable program code can comprise instructions that, whenexecuted by a computer, control the manufacturing equipment (e.g.,lithography equipment, implantation chambers, etch chambers, etc.) usedin the manufacturing of integrated circuits and, more specifically,cause such manufacturing equipment to perform the above-describedmethod.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments herein will be better understood from the followingdetailed description with reference to the drawings, which are notnecessarily drawn to scale and in which:

FIG. 1 is a flow diagram illustrating an embodiment of a patterningmethod;

FIG. 2 is a perspective diagram illustrating a substrate to be patternedusing the patterning method set forth in the flow diagram of FIG. 1;

FIG. 3 is a perspective diagram illustrating process 104 of thepatterning method of FIG. 1;

FIG. 4 is a perspective diagram illustrating process 106 of thepatterning method of FIG. 1;

FIG. 5 is a perspective diagram illustrating processes 108-110 of hepatterning method of FIG. 1;

FIG. 6 is a perspective diagram illustrating process 112 in thepatterning method of FIG. 1;

FIG. 7 is a perspective diagram illustrating processes 114-118 in thepatterning method of FIG. 1;

FIG. 8 is a perspective diagram illustrating process 120 in thepatterning method of FIG. 1;

FIG. 9 is a perspective diagram illustrating process 122 in thepatterning method of FIG. 1;

FIG. 10 is a perspective diagram illustrating a first mask layer dopedusing the masked dopant implantation processes 106 such that theresulting undoped regions have a same size and shape;

FIG. 11 is a perspective diagram illustrating a first mask layer dopedusing the masked dopant implantation processes 106 such that at leastsome of the resulting undoped regions have different sizes and shapes;

FIG. 12 is a perspective diagram illustrating process 124 and,particularly, selective removal of the undoped regions of the first masklayer, in the patterning method of FIG. 1;

FIG. 13 is a perspective diagram illustrating process 126 in thepatterning method of FIG. 1 so as to form openings (e.g., vias ortrenches) in the substrate;

FIG. 14 is a perspective diagram illustrating process 124 and,particularly, selective removal of the doped region of the first masklayer, in the patterning method of FIG. 1;

FIG. 15 is a perspective diagram illustrating process 126 in thepatterning method of FIG. 1 so as to form mesas in the substrate;

FIG. 16 is a perspective diagram illustrating the mesas of FIG. 15following removal of the remaining undoped regions of the first masklayer; and

FIG. 17 is representative hardware environment that can be used toexecute the computer program code that controls the manufacturingequipment used in the performance of the patterning method of FIG. 1.

DETAILED DESCRIPTION

As mentioned above, as semiconductor device size scaling continues, theability to form devices or components thereof with small dimensions hasbecome more and more challenging. One solution for achieving highresolution is double patterning. Conventional double patterning involvesdouble exposure and double etch (DPDE) process. That is, a first mask isformed using conventional lithographic patterning techniques followed bya first etch process. Then, a second mask is formed using conventionallithographic patterning techniques followed by a second etch process.Unfortunately, the wafer topography after the first etch processes maynegatively impact the formation of the second mask convention due toreduced depth focus and result in overlay errors. Therefore, there is aneed in the art for an improved double patterning technique that avoidssuch wafer topography effects.

In view of the foregoing, disclosed herein are embodiments of animproved double patterning method for forming openings (e.g., vias ortrenches) or mesas (e.g., three dimensional bodies, pillars, bars, etc.)on a substrate. This method avoids the wafer topography effects seen inprior art double patterning techniques by ensuring that the substrateitself is only subjected to a single etch process. Specifically, in theembodiments disclosed herein, a first mask layer is formed on thesubstrate and subjected to multiple masked implantation processes suchthat it has a doped region and multiple undoped regions within (i.e.,defined by) the doped region. Then, either the undoped regions or thedoped region can be selectively removed in order to form a mask patternabove the substrate. Once the mask pattern is formed, an etch processcan be performed to transfer the mask pattern into the substrate.Depending upon whether the undoped regions are removed or the dopedregion is removed, the mask pattern will form openings or mesas,respectively, on the substrate.

Referring to the flow diagram of FIG. 1, generally, each of the methodembodiments disclosed herein can comprise providing a substrate 201(102, see FIG. 2). This substrate 201 can comprise any material layerrequiring patterning with openings (e.g., vias or trenches), mesas(i.e., three dimensional bodies, pillars, bars, etc.), or any otherpatterns. For example, the substrate 201 can comprise a bulksemiconductor substrate (e.g., a bulk silicon substrate or any otherbulk semiconductor substrate) requiring patterning with trenches forsubsequent formation of trench isolation structures (e.g., shallowtrench isolation structures and/or deep trench isolation structures).Alternatively, the substrate 201 can comprise a semiconductor layer orconductor layer above a semiconductor substrate and requiring patterningwith mesas for subsequent formation of, for example, vertical nanowiresor gate structures. Alternatively, the substrate 201 can comprise adielectric layer, such as a back end of the line (BEOL) dielectriclayer, requiring patterning with vias for subsequent formation ofcontacts or interconnects and/or requiring patterning with trenches forsubsequent wire formation. It should be understood that the above listof materials requiring pattern is offered for illustration purposes andis not intended to be limiting. The disclosed method could alternativelybe implemented for patterning of openings and/or mesas in any othersuitable material and/or for any other suitable purpose.

In order to pattern this substrate 201, a first mask layer 211 can beformed (e.g., deposited) on the substrate 201 (104, see FIG. 3). Thisfirst mask layer 211 can comprise any suitable material within whichdoped and undoped regions can be formed, as discussed in detail below,and which can be etched to selectively remove either the doped orundoped regions, also as discussed in detail below. For example, thefirst mask layer 211 can comprise an amorphous semiconductor layer orpolycrystalline semiconductor layer, such as an amorphous silicon layeror a polycrystalline silicon layer. Optionally, the first mask layer 211can be planarized, for example, by chemical mechanical polishing (CMP),to ensure that it has a planar top surface and an essentially uniformthickness.

Then, at least two masked dopant implantation processes can be performedin order to form, within the first mask layer 211, a doped region 221that laterally surrounds (i.e., defines the outer edges of, borders,etc.) multiple undoped regions 222 (106, see FIG. 4).

Specifically, in each of the embodiments disclosed herein, the maskeddopant implantation processes 106 can comprise forming (e.g.,depositing) a second mask layer 212 on the first mask layer 211 and,then, patterning the second mask layer 212 such that first portions 231of the first mask layer 211 are exposed (108-110, see FIG. 5). Asillustrated in FIG. 5, in one embodiment, the pattern of the second masklayer can comprise a plurality of parallel rectangular bodies (alsoreferred to herein as a stripe mask pattern), wherein each body has asame width and wherein the spacing between adjacent bodies isessentially identical. However, it should be understood that the patternof the second mask layer may vary from the exemplary stripe mask patternillustrated. For example, the spacing between adjacent bodies in thepattern may differ, the widths of the bodies in the pattern may differ,the bodies in the pattern may be non-parallel, the bodies in the patternmay not be rectangular, the bodies in the pattern may not be continuous(e.g., each rectangular body as shown may be replaced with multiplerectangular bodies that are aligned but spaced apart), etc.

A first dopant implantation process can then be performed to dope theexposed first portions 231 of the first mask layer 212 with a dopant,thereby forming doped first portions 241 (112, see FIG. 6). After thefirst dopant implantation process 112, the second mask layer 212 can beselectively removed (114).

Next, a third mask layer 213 can be formed (e.g., deposited) on thefirst mask layer 211 and, then, patterned so as to expose secondportions 231 of the first mask layer 211. Specifically, the third masklayer 213 can be patterned so that the exposed second portions 232traverse (i.e., cross) the doped first portions 241 (116-118, see FIG.7). As illustrated in FIG. 7, in one embodiment, the pattern of thethird mask layer 213 can, like the pattern of the second mask layer 212,comprise a plurality of parallel rectangular bodies (i.e., can be astripe mask pattern), wherein each body has a same width and wherein thespacing between adjacent bodies are essentially identical. However, itshould be understood that the pattern of the second mask layer maydiffer from the exemplary pattern illustrated. For example, the spacingbetween adjacent bodies in the pattern may differ, the widths of thebodies in the pattern may differ, the bodies in the pattern may benon-parallel, the bodies in the pattern may not be rectangular, thebodies in the pattern may not be continuous (e.g., each rectangular bodyas shown may be replaced with multiple rectangular bodies that arealigned but spaced apart), etc. Also, as illustrated in FIG. 7, thepattern of the third mask layer 213 can be such that the exposed secondportions 232 of the first mask layer 211 are perpendicular to thepreviously doped first portions 241 of the first mask layer 211.Alternatively, the pattern of the third mask layer 213 may be such thatthe exposed second portions 232 of the first mask layer 211 are notperpendicular to the previously doped first portions 241 (e.g., suchthat the exposed second portions 232 are angled at a 45 degree angle orsome other angle relative to the previously doped first portions 241).Since the third mask layer 213 is formed on the planar surface of thefirst mask layer 212, topography effects are avoided.

Then, a second dopant implantation process can be performed in order todope the exposed second portions 232 of the first mask layer 211 withthe dopant, thereby forming doped second portions 242 (120, see FIG. 8).After the second dopant implantation process 120, the third mask layer213 can be removed (122, see FIG. 9). As illustrated in FIG. 9, thedoped first portions 241 and the doped second portions 242 incombination form the doped region 221 that laterally surrounds (i.e.,defines the outer edges of, borders, etc.) multiple undoped regions 222.

It should be noted that patterning of the second mask layer 212 atprocess 110 and patterning of the third mask layer 213 at process 118can be achieved through conventional lithographic patterning techniquesor, alternatively, can be achieved through conventional sidewall imagetransfer techniques. Such patterning techniques are well known in theart and, thus, the details thereof are omitted from this specificationin order to allow the reader to focus on the salient aspects of theembodiments. Those skilled in the art will recognize that the materialused for the second mask layer 212 and the third mask layer 213 may varydepending upon the patterning technique used. For example, iflithographic patterning techniques are used, the second mask layer 212and third mask layer 213 may comprise photoresist layers; whereas ifsidewall image transfer patterning techniques are used, the second masklayer 212 and third mask layer 213 may comprise dielectric layers (e.g.,nitride layers).

Additionally, it should be noted that, if the patterns of the secondmask layer 212 and the third mask layer 213 each comprise a plurality ofparallel rectangular bodies (e.g., a stripe mask pattern), if theserectangular bodies all have the same width and if the spacing betweenadjacent bodies is essentially identical, then the resulting undopedregions 222 will each have approximately the same size and shapefollowing the second dopant implantation process 120. For example, asshown in FIG. 9, the undoped regions 222 may all be the same size andsquare (or rectangular) in shape, particularly when the pattern of thethird mask layer 213 was oriented perpendicular to the pattern of thesecond mask layer 212 (i.e., particularly when the pattern of the thirdmask layer 213 was oriented such that the exposed second portions 232were perpendicular to the doped first portions 241 prior to the seconddopant implantation process 118). Those skilled in the art will,however, recognize that this shape may change (e.g., to a diamond shapefollowing the second dopant implantation process 118) if the pattern ofthe third mask layer 213 was not oriented perpendicular to the patternof the second mask layer 212 (e.g., if the pattern of the third masklayer 213 was oriented such that the exposed second portions 232 were atan angle, such as a 45 degree angle, relative to the doped firstportions 241) (see FIG. 10).

Additionally, as mentioned above, the pattern of the second mask layer212 and/or the pattern of the third mask layer 213 may differ from thepatterns illustrated in FIGS. 5 and 7, respectively. For example, thespacing between adjacent bodies in the pattern may differ, the widths ofthe bodies in the pattern may differ, the bodies in the pattern may benon-parallel, the bodies in the pattern may not be rectangular, thebodies in the pattern may not be continuous (e.g., each rectangular bodyas shown may be replaced with multiple rectangular bodies that arealigned but spaced apart), etc. If this is the case, some of theresulting undoped regions 222 following the second dopant implantationprocess 118 may vary in size and/or shape (e.g., see FIG. 11 having bothsquare and rectangular undoped regions 222).

Next, regardless of the sizes and/or shapes of the undoped regions 222within the doped region 221, either the undoped regions 222 or the dopedregion 221 can be selectively removed in order to form a mask patternabove the substrate 201 (124). Once the mask pattern is formed, a singleetch process can be performed in order to transfer the mask pattern intothe substrate 201, thereby forming either openings (e.g., vias ortrenches) or mesas (e.g., three dimensional bodies, pillars, bars, etc.)in the substrate 201 (126). For illustration purposes, these processes124-126 are described in greater detail below and illustrated in theFigures with respect to the first mask layer 211, as shown in FIG. 4 (orFIG. 9), wherein the undoped regions 222 all have approximately the samesize and square shape. However, it should be understood that these sameprocesses may similarly applied to the structures shown in FIGS. 10 and11, wherein the undoped regions 222 have different shape (e.g., adiamond shape) or have different sizes and/or shapes, respectively.

More particularly, in each of the embodiments disclosed herein, eitherthe multiple undoped regions 222 or the doped region 221 of the firstmask layer 211 can be selectively removed at process 124. Depending uponwhether the undoped regions 222 are removed or the doped region 221 isremoved, the resulting mask pattern can be used during a single etch atprocess 126 to form openings (e.g., vias or trenches) or mesas (e.g.,three dimensional bodies, pillars, bars, etc.), respectively, on thesubstrate 201 at process 126. To optimize the selective removal process,the dopant used in the dopant implantation processes described above canbe selected to facilitate either selective removal of the undopedregions over the doped region for subsequent formation of openings(e.g., vias or trenches) in the substrate or selective removal of thedoped region for subsequent formation of mesas (i.e., three dimensionalbodies, pillars, bars, etc.) in the substrate 201.

For example, in one embodiment, the patterning method as set forth inthe flow diagram of FIG. 1, can comprise providing a substrate 201 atprocess 102, as discussed in detail above and illustrated in FIG. 2. Afirst mask layer 211 (e.g., an amorphous or polycrystallinesemiconductor layer, such as an amorphous or polycrystalline siliconlayer) can be formed (e.g., deposited) on the substrate 201 at process104, as described in detail above and illustrated in FIG. 3. Then, atleast two masked dopant implantation processes 106 can be performed inorder to form, within the first mask layer 211, a doped region 221,which laterally surrounds (i.e., defines the outer edges of, borders,etc.) multiple undoped regions 222, as described in detail above andillustrated in FIG. 4. Next, the multiple undoped regions 222 can beselectively removed in order to form a mask pattern with openings 251above the substrate 201, as described in detail above at process 124 andillustrated in FIG. 12. In this case, the dopant used in the dopantimplantation processes 106 to form the doped region 221 should bepreselected to ensure that the undoped regions 222 can be selectivelyetched over the doped region 221. Thus, when the first mask layer 221comprises amorphous silicon or polycrystalline silicon, boron or xenoncan, for example, be preselected as the dopant to be used in the dopantimplantation processes 106 because undoped silicon can be readilyselectively etched over boron-doped or xenon-doped silicon. For example,a wet etch, such as ammonia or TetraMethyl Ammonium Hydroxide (TMAH)etch, can be used to etch undoped silicon so that it can be removedselective to boron-doped or xenon-doped silicon.

Once the mask pattern with the openings 251 is formed, a single etchprocess can be performed in order to transfer the mask pattern into thesubstrate 201, thereby forming openings (e.g., vias) 252 in thesubstrate 201 and the mask pattern can be removed (126, see FIG. 13).This single etch process can be pre-selected based on the material ofthe substrate 201 and the desired shape of the openings 252 to be formedwithin the substrate 201. Various different etch processes that aresuitable for forming openings within a dielectric, conductor orsemiconductor substrate with the assistance of a mask pattern are wellknown in the art and, thus, the details of such etch processes areomitted from this specification in order to allow the reader to focus onthe salient aspects of the embodiment.

In another embodiment, the patterning method as set forth in the flowdiagram of FIG. 1, can comprise providing a substrate 201, as discussedin detail above and illustrated in FIG. 2. A first mask layer 211 (e.g.,an amorphous or polycrystalline semiconductor layer, such as anamorphous or polycrystalline silicon layer) can be formed on thesubstrate 201 at process 104, as described in detail above andillustrated in FIG. 3. Then, at least two masked dopant implantationprocesses 106 can be performed in order to form, within the first masklayer 211, a doped region 221, which laterally surrounds (i.e., definesthe outer edges of, borders, etc.) multiple undoped regions 222, asdescribed in detail above and illustrated in FIG. 4. Next, the dopedregion 221 can be selectively removed in order to form a mask patternwith discrete mask bodies 261 above the substrate 201, as described indetail above at process 124 and illustrated in FIG. 14. In this case,the dopant used in the dopant implantation processes 106 to form thedoped region 221 should be preselected to ensure that the doped region221 can be selectively etched over the undoped regions 222. Thus, whenthe first mask layer 211 comprises amorphous silicon or polycrystallinesilicon, arsenic or phosphorous can be preselected as the dopant to beused in the dopant implantation processes 106 because arsenic-doped orphosphorous-doped silicon can be readily selectively etched over undopedsilicon. For example, a dry etch, such as plasma etch with a gas mixtureof CF4, O2, Cl2, and/or HBr, can be used to etch phosphorus-doped orarsenic-doped silicon so that it can be removed selective to undopedsilicon.

Once the mask pattern with the discrete mask bodies 261 is formed, asingle etch process can be performed in order to transfer the maskpattern into the substrate 201, thereby forming, in the substrate, mesas262 (i.e., three-dimensional bodies, pillars, bars, etc.) having thesame shapes as the discrete mask bodies and the mask pattern can beremoved (126, see FIGS. 15-16). It should be noted that, as illustrated,this etch process can be performed so that the mesas 262 are formed onlyin the upper portion of the substrate 201. However, it should beunderstood that, alternatively, the etch process can stop at any desiredpoint within the substrate 201 including, but not limited to, the bottomsurface of the substrate 201. This single etch process can bepre-selected based on the material of the substrate 201 and the desiredshape of the mesa sidewalls (e.g., vertical (as illustrated), angled,tapered, etc.). Various different etch processes that are suitable forforming such mesas from a dielectric, conductor or semiconductorsubstrate with the assistance of a mask pattern are well known in theart and, thus, the details of such etch processes are omitted from thisspecification in order to allow the reader to focus on the salientaspects of the embodiment.

Also disclosed herein are embodiments of a computer program product.This computer program product can comprise a computer-readable mediumhaving computer-readable program code embodied therewith. Thecomputer-readable program code can comprise instructions that, whenexecuted by a computer, control the manufacturing equipment (e.g.,lithography equipment, implantation chambers, etch chambers, etc.) usedin the manufacturing of integrated circuits and, more specifically,cause such manufacturing equipment to perform the above-describedmethod.

More particularly, any combination of one or more computer-readablemedium(s) may be utilized. The computer-readable medium may be acomputer-readable storage medium and, thereby, non-transitory, or may bea computer-readable signal medium. A computer-readable storage mediummay be, for example, but is not limited to, an electronic, magnetic,optical, electromagnetic, infrared, or semiconductor system, apparatus,or device, or any suitable combination of the foregoing. More specificexamples (a non-exhaustive list) of the computer-readable storage mediumwould include the following: an electrical connection having one or morewires, a portable computer diskette, a hard disk, a random access memory(RAM), a read-only memory (ROM), an erasable programmable read-onlymemory (EPROM or Flash memory), an optical fiber, a portable compactdisc read-only memory (CD-ROM), an optical storage device, a magneticstorage device, or any suitable combination of the foregoing. In thecontext of this document, a computer-readable storage medium may be anytangible medium that can contain, or store a program for use by or inconnection with an instruction execution system, apparatus, or device. Acomputer-readable signal medium may include a propagated data signalwith computer-readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer-readable signal medium may be any computer-readable medium thatis not a computer-readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer-readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing. Computer program code for carrying out operations foraspects of the disclosed embodiments may be written in any combinationof one or more programming languages, including an object orientedprogramming language such as Java, Smalltalk, C++ or the like andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The program codemay execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Aspects of the disclosed embodiments are described above with referenceto flowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products. It will be understood that eachblock of the flowchart illustrations and/or D-2 block diagrams, andcombinations of blocks in the flowchart illustrations and/or blockdiagrams, can be implemented by computer program instructions. Thesecomputer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

These computer program instructions may also be stored in acomputer-readable medium that can direct a computer, other programmabledata processing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer-readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks. The computer program instructions may also beloaded onto a computer, other programmable data processing apparatus, orother devices to cause a series of operational steps to be performed onthe computer, other programmable apparatus or other devices to produce acomputer implemented process such that the instructions which execute onthe computer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

A representative hardware environment for executing the computer programcode, as described in detail above, is depicted in FIG. 17. Thisschematic drawing illustrates a hardware configuration of an informationhandling/computer system. The system comprises at least one processor orcentral processing unit (CPU) 10. The CPUs 10 are interconnected viasystem bus 12 to various devices such as a random access memory (RAM)14, read-only memory (ROM) 16, and an input/output (I/O) adapter 18. TheI/O adapter 18 can connect to peripheral devices, such as disk units 11and tape drives 13, or other program storage devices that are readableby the system. The system can read the inventive instructions on theprogram storage devices and follow these instructions to execute themethodology of the embodiments of the invention. The system furtherincludes a user interface adapter 19 that connects a keyboard 15, mouse17, speaker 24, microphone 22, and/or other user interface devices suchas a touch screen device (not shown) to the bus 12 to gather user input.Additionally, a communication adapter 20 connects the bus 12 to a dataprocessing network 25, and a display adapter 21 connects the bus 12 to adisplay device 23 which may be embodied as an output device such as amonitor, printer, or transmitter, for example.

It should be understood that the flowchart and block diagrams in theFigures illustrate the architecture, functionality, and operation ofpossible implementations of methods and computer program productsaccording to various embodiments disclosed. In this regard, each blockin the flowchart or block diagrams may represent a module, segment, orportion of code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

It should be understood that as used herein, the singular forms “a”,“an” and “the” are intended to include the plural forms as well, unlessthe context clearly indicates otherwise. It should further be understoodthat the terms “comprises” “comprising”, “includes” and/or “including”,as used in this specification, specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. Additionally, it should be understood that the correspondingstructures, materials, acts, and equivalents of all means or step plusfunction elements in the claims below are intended to include anystructure, material, or act for performing the function in combinationwith other claimed elements as specifically claimed. The description ofthe disclosed embodiments has been presented for purposes ofillustration and is not intended to be exhaustive. Many modificationsand variations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosedembodiments.

Therefore, disclosed above are embodiments of an improved doublepatterning method for forming openings (e.g., vias or trenches) or mesason a substrate. This method avoids the wafer topography effects seen inprior art double patterning techniques by ensuring that the substrateitself is only subjected to a single etch process. Specifically, in theembodiments disclosed herein, a first mask layer is formed on thesubstrate and subjected to multiple masked implantation processes suchthat it has a doped region and multiple undoped regions within (i.e.,defined by) the doped region. Then, either the undoped regions or thedoped region can be selectively removed in order to form a mask patternabove the substrate. Once the mask pattern is formed, an etch processcan be performed to transfer the mask pattern into the substrate.Depending upon whether the undoped regions are removed or the dopedregion is removed, the mask pattern will form openings (e.g., vias ortrenches) or mesas, respectively, on the substrate.

The advantage of the above-described embodiments is that, the substratesurface remains planar during the masked implantation processes and,thus, issues regarding topography effects are avoided.

What is claimed is:
 1. A computer program product comprising acomputer-readable storage medium storing computer-readable program code,said computer-readable program code comprising instructions that, whenexecuted by a computer, cause manufacturing equipment to perform amethod, said method comprising: forming a first mask layer on asubstrate; performing at least two dopant implantation processes toform, within said first mask layer, a doped region that comprises adopant and that laterally surrounds multiple undoped region; selectivelyremoving said doped region to form a mask pattern above said substrate;and, performing an etch process to transfer said mask pattern into saidsubstrate to form multiple discrete features in said substrate, saiddopant comprising phosphorous.
 2. The computer program product of claim1, said performing of said at least two dopant implantation processescomprising: forming a second mask layer on said first mask layer, saidsecond mask layer being patterned so that first portions of said firstmask layer are exposed; doping said first portions with said dopant;removing said second mask layer; forming a third mask layer on saidfirst mask layer, said third mask layer being patterned such that secondportions of said first mask layer, which traverse said first portions,are exposed; doping said second portions with said dopant such that saidfirst portions and said second portions in combination form said dopedregion that comprises said dopant and that laterally surrounds saidmultiple undoped regions; and, removing said third mask layer.
 3. Thecomputer program product of claim 2, said second mask layer and saidthird mask layer each being formed such that, following said doping ofsaid first portions and said doping of said second portions, saidmultiple undoped regions each have a same size and shape.
 4. Thecomputer program product of claim 2, said second mask layer and saidthird mask layer each being formed such that, following said doping ofsaid first portions and said doping of said second portions, at leastsome of said multiple undoped regions have any of different sizes anddifferent shapes.
 5. The computer program product of claim 2, saidsecond mask layer being patterned into a strip mask pattern and saidthird mask layer being patterned into an additional strip mask patternoriented at a different angle than said stripe mask pattern, said stripemask pattern and said additional stripe mask pattern each comprising aplurality of parallel rectangular-shaped bodies and said parallelrectangular-shaped bodies having identical dimensions and spacing insaid stripe mask pattern and said additional stripe mask pattern.
 6. Thecomputer program product of claim 2, said second mask layer beingpatterned into a strip mask pattern and said third mask layer beingpatterned into an additional strip mask pattern oriented at a differentangle than said stripe mask pattern, said stripe mask pattern and saidadditional stripe mask pattern each comprising a plurality of parallelrectangular-shaped bodies and said parallel rectangular-shaped bodieshaving any one of varied dimensions and varied spacing in said stripemask pattern and said additional stripe mask pattern.
 7. The computerprogram product of claim 1, said first mask layer comprising any one ofan amorphous semiconductor layer and a polycrystalline semiconductorlayer and said substrate comprising any one of a dielectric, a conductorand a semiconductor.
 8. The computer program product of claim 2, saidsecond mask layer and said third mask layer being patterned usinglithographic patterning techniques and comprising comprising photoresistlayers.
 9. The computer program product of claim 2, said second masklayer and said third mask layer being patterning using sidewall imagetransfer patterning techniques and comprising dielectric layers.
 10. Acomputer program product comprising a computer-readable storage mediumstoring computer-readable program code, said computer-readable programcode comprising instructions that, when executed by a computer, causemanufacturing equipment to perform a method, said method comprising:forming a first mask layer on a substrate; performing at least twodopant implantation processes to form, within said first mask layer, adoped region that comprises a dopant and that laterally surroundsmultiple undoped regions; selectively removing said multiple undopedregions to form a mask pattern above said substrate; and, performing anetch process to transfer said mask pattern into said substrate to formmultiple openings in said substrate, said dopant comprising xenon. 11.The computer program product of claim 10, said performing of said atleast two dopant implantation processes comprising: forming a secondmask layer on said first mask layer, said second mask layer beingpatterned such that first portions of said first mask layer are exposed;doping said first portions with said dopant; removing said second masklayer; forming a third mask layer on said first mask layer, said thirdmask layer being patterned such that second portions of said first masklayer, which traverse said first portions, are exposed; doping saidsecond portions with said dopant such that said first portions and saidsecond portions in combination form said doped region that comprisessaid dopant and that laterally surrounds said multiple undoped regions;and, removing said third mask layer.
 12. The computer program product ofclaim 11, said second mask layer and said third mask layer each beingformed such that, following said doping of said first portions and saiddoping of said second portions, said multiple undoped regions each havea same size and shape.
 13. The computer program product of claim 11,said second mask layer and said third mask layer each being formed suchthat, following said doping of said first portions and said doping ofsaid second portions, at least some of said multiple undoped regionshave any of different sizes and different shapes.
 14. The computerprogram product of claim 11, said second mask layer being patterned intoa strip mask pattern and said third mask layer being patterned into anadditional strip mask pattern oriented at a different angle than saidstripe mask pattern, said stripe mask pattern and said additional stripemask pattern each comprising a plurality of parallel rectangular-shapedbodies and said parallel rectangular-shaped bodies having identicaldimensions and spacing in said stripe mask pattern and said additionalstripe mask pattern.
 15. The computer program product of claim 11, saidsecond mask layer being patterned into a strip mask pattern and saidthird mask layer being patterned into an additional strip mask patternoriented at a different angle than said stripe mask pattern, said stripemask pattern and said additional stripe mask pattern each comprising aplurality of parallel rectangular-shaped bodies and said parallelrectangular-shaped bodies having any one of varied dimensions and variedspacing in said stripe mask pattern and said additional stripe maskpattern.
 16. The computer program product of claim 10, said first masklayer comprising any one of amorphous silicon and polycrystallinesilicon and said substrate comprising any one of a dielectric, aconductor and a semiconductor.
 17. The computer program product of claim11, said second mask layer and said third mask layer being patternedusing lithographic patterning techniques and comprising comprisingphotoresist layers.
 18. The computer program product of claim 11, saidsecond mask layer and said third mask layer being patterning usingsidewall image transfer patterning techniques and comprising dielectriclayers.
 19. A computer program product comprising a computer-readablestorage medium storing computer-readable program code, saidcomputer-readable program code comprising instructions that, whenexecuted by a computer, cause manufacturing equipment to perform amethod, said method comprising: forming a first mask layer on asubstrate, said substrate comprising a conductor layer; performing atleast two dopant implantation processes to form, within said first masklayer, a doped region that comprises a dopant and that laterallysurrounds multiple undoped regions, said performing of said at least twodopant implantation processes comprising: forming a second mask layer onsaid first mask layer, said second mask layer being patterned such thatfirst portions of said first mask layer are exposed; doping said firstportions with said dopant; removing said second mask layer; forming athird mask layer on said first mask layer such that second portions ofsaid first mask layer are exposed; doping said second portions with saiddopant such that said first portions and said second portions incombination form said doped region that comprises said dopant and thatlaterally surrounds said multiple undoped regions; and, removing saidthird mask layer; selectively removing said doped region to form a maskpattern above said substrate; and performing an etch process to transfersaid mask pattern into said substrate so as to form multiple discretenanowires in said conductor layer.
 20. The computer program product ofclaim 19, and said dopant comprising any of arsenic and phosphorous andsaid first mask layer comprising any one of amorphous silicon andpolycrystalline silicon.